This project is a continued effort to isolate from soybeans a substance, or a class of substances, which markedly reduces the rate of growth of non-contact inhibited cells (L and HeLa cells) in culture. Thirty micrograms per milliliter of the partly purified substance reduces the growth rate of L cells in suspension culture by more than 85% without evidence of cytotoxic effects. The active component is soluble in chloroform-methanol (2:l); for this and other reasons it is believed that the active component is a complex glycolipid that exerts its action at the cell surface. It is expected that the elucidation of the chemical composition and the mode of action of the active substance will help in our understanding of molecular events relating the cell membrane to cell division. Also, it may assist in the development of cancer chemotherapeutic agents or regimens.